Get tax affairs back on track if you missed the self assessment deadline

11 Feb 2026

The Low Incomes Tax Reform Group (LITRG) is urging the estimated one million taxpayers who failed to file their tax return on time to get their tax affairs back on track.

HMRC says that around one million customers missed the cut-off date.

Failing to meet the self assessment deadline carries an automatic £100 late filing penalty, with further penalties at stake the longer the return remains outstanding.

The LITRG recommends four steps to get tax affairs back on track:

• Checking whether a return is even needed.
• Filing outstanding returns as soon as possible.
• Paying tax as soon as possible will prevent additional penalties for late payment.
• If taxpayers have a reasonable excuse for not meeting the deadline, they usually have 30 days to appeal any penalties charged.

Antonia Stokes, LITRG Senior Manager, said: 'Missing the self assessment deadline can feel daunting or worrying, and some people might be unsure how to put things right.

'But there are some practical steps people can take. This includes working out whether a return was even needed in the first place. If it was, then it is better to act now by filing the return and paying the tax, penalties and interest charges that are due. Payment plans are available to help people who might not be able to settle their tax bill in full.

'If they have what is called a reasonable excuse, it might even be possible to appeal the penalty, but they will still need to file their tax return as soon as possible.'